1. Field of the Invention
The present invention relates to an organic light-emitting device such as a spatial light modulator, a light neural network device and etc. used for an optical computing device and a light emitting type display, a method for preparing the same.
2. Description of the Related Art
The light-emitting device generally includes 1) a light emitting display device constituting a light-emitting layer between a lower electrode on a base plate and a upper electrode, 2) an electric field light emitting device constituting a light emitting layer laminated on a carrier transport layer supported by a base plate and 3) a spatial light modulator type device constituting a lower electrode on a base plate and a light-emitting layer, a carrier transport layer and a transparent electrode which are laminated in turn on the lower electrode.
Recently, it is reported that a preparation trial of an organic light emitting device was made by using an organic compound as a necessary constituent. For example, the L256 page of Japanese Journal of Applied phisics 27(2)(1988 discloses an electric field light emitting device having a laminated structure provided with an organic light emitting layer and a carrier transport layer as the above type 2). In the device, a semi-transparent lower electrode of Au is mounted on a glass base plate and thereon are mounted in turn many layers, which are a hole transort layer of N,N'-diphenyl-N,N'-(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (hereinafter referred to as TPD) having a 2000 .ANG. coating, an organic light emitting layer and an electron transport layer of perylene-tetracarboxyl group derivatives, the latter two layers being 1000 .ANG. coating in thickness.
Further, the upper electrode comprises Mg coating. A bright light emission was observed by applying an electrostatic field to the lower and upper electrodes when phthaloperynone derivatives is used as a material of the organic light emitting layer (see the priprint for the 35th Spring Lecture Meeting of the Applied Physics Society). The emitting light can be varied depending on a material of the organic light emitting layer to be selected.
Further, as to the above type 3) it is reported that another organic light emitting device constituted by using an amorphous alloy of Si.sub.1-x C.sub.x :H as a light emitting type spatial light modulator used for an optical computing device and so on (see the priprint for the 37th Spring Lecture Meeting of the Applied Physics Society).
In the reported device, lamination of a carrier transport layer and a light emitting layer make the number of electron inplating increased and thus make luminous efficiency thereof improved in comparison of the convenient organic light emitting device, but the efficiency is below 0.5% and more development is needed. Further, change with time of luminous brightness is large and especially there comes to arise problems such as lowering of electron inplating efficiency for the light emitting layer and accumulation of spatial carrier in the carrier transport layer.
The lowering of luminous brightness is caused by the following factors:
1) quenching caused by crystallization of the molecule constituting light emitting layer.
2) decomposition of the molecule constituting a light emitting layer caused by the reaction thereof with oxygen molecule and so on.
3) obstruction of electron inplating from outside caused by the accumulation of carrier in the light emitting layer.